Lamp.



W. H. WOOD.

LAMP.

APPLICATION FILED mu 5. 1916.

1,235,275 Patented July 31, 1917.

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W. H. WOOD.

LAMP.

APPLICATION man MAY 5. 19m.

2 SHEETS-SHEET 2.

1,235,275 Patented July 31, 1917.

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LAMP.

Specification of Letters Patent.

Application filed May 5, 1916. Serial No. 95,542.

To all whom it may concern:

Be it known that I, WILLIAM a citizen of the United States, residing at Cleveland, in the county of Cuyahoga and State ofOhio, have invented a certain new and useful Improvement inLamps, of which the following is a full, clear, and exact description, reference being had to the accompanying drawings.

This invention relates to lamps and more particularly to. the lamps which are employed on motor vehicles. Safety and convenience of vehicle operation in the dark requires a strong and uniform illumination of the ground for a considerable distance in front of the machine, yet also requires keeping the rays of light sufliciently low to avoid blinding the eyes of men and animals moving in the opposite direction. Most expedients heretofore adopted satisfy the second -requirement by sacrificing the first requireis the provision of a as to secure a true scientific pro ect1on of ment in some way, either by so changing the focus of the light rays as largely to neutralize their forward projection, or by employing an obscure coating over the face of the the present invention lamp.

eflector of such nature The object oi the light in the distribution desired, for a great distance in front of the automob1le and in a uniform manneruas regards the ground, while directing all the rays downwardly so as to avoid the blinding heretofore mentioned the provision with a single light source of a plurality of main reflecting sys- .tems and intermediate systems interposed between the main systems to form a transltion from one to the other; the provision of a reflector system in which a maximum of efficiency of light projection and distribution shall be secured; while further obyects and advantages of the invention will become apparent as the description proceeds.

In the drawings accompanying and forming a part of this application I have illustrated certain lamp reflectors constructed in accordance with my invention, together with certain diagrammatic viewsillustrating the scientific theory of the same. In these drawings, Figure l is a perspective view of a reflector constructed in, accordance with my invention, a lamp bulb being illustrated in dotted lines therein; Fig. 2 is a vertical sectional view through the center of the reflector shown in Fig. 1 and drawn to larger scale; Fig. 3 represents a front elevation of H. Wooo,

the said reflector; Fig. et is a' perspective new of a modified form of reflector constructed in accordance with my invention; Fig. 5 is a vertical sectional view through the centerpf the reflector shown in Fig. l; Flg. 6 is a diagrammatic view showing the mode of reflection of light rays derived from sources located at different positions along the axis of a parabolic reflector; Fig. 7 is a diagrammatic view illustrating the mode of reflection of light rays derived from a source displaced from the axis of a parabolic reflector; Fig. 8 is a diagrammatic view showing one half of a parabolic reflector with thelight source. arranged upon its axis and slightly forward of the focus; Fig. 9 is a view of the opposite half of a parabolic reflectorslightly inclined to the horizontal and having its light source above the axis; Fig.

'10 illustrates a combination of 'the 'two resource placed exactly at this focus will be.

reflected forwardly in strictly parallel lines as shown 'by the full lines in Fig. 6; all light rays emanating from a source located on the axis outside of the focal point, as at S will be converged as shown by the dotted lines in Fig. 6, though not toward any single point; and all light rays emanating from a light source located along the parabolic axis inside of the focal point will be diverged after reflection as indicated by the dotanddash lines in Fig. 6.

Referring next to F ig. 7 wherein A represents the same parabolic reflector, ara its major axis and F its focal point, if the light source be moved to one side of the axis as-to'the point S3, all rays emanating therefrom will be thrown toward the opposite side of'the axis aa. Thus if the line a a considered as horizontal and the source S elevated above that axis the reflected rays will have a downward tendency, which tendency will be present regardless as to whether the source be located at the point S which is substantially upon the parameter or be located outside or inside of the same as indicated at S, S respectively, al-

lower surface; and while it is necessary to If it be attempted though-the dispersion or convergence of the light rays will be modifiedlslightly.

Therefore if a half para ola be taken as shown at B in Fig. 8, and a light source'S be placed upon its axis bb but at a oint outside of its focus there will be a tendbncy for the light to be thrown outward .and slightly converged; plementa-ry half of a similar parabola as C in Fig. 9 be located with its axis'cc inlclin'ed to the horizontal HH and be pro: vided with lightfrom a source S placed above itsaxis'and withinits focal point, the light rays reflected thereby will have a downward tendency for three reasons; the

--ci nclination of the reflecting surface, the location of the source above the axis, and the location of the source at the rear of the focal point. r

Hence it is entirfiy feasible to combine these two half parabolas into a single whole as shown in Fig. 10, since the inclination of the axes will cause a light source S which is exactly upon the axis bb of the upper surface to fall above the'axis' c--0 ofthe the best results to locate the source forward of the focal point of the upper parabola and rearwardly of the focal'point. of the lower parabola, this can easily I 7 ing the lower parabola of slightly larger size so that its focal point fall ahead of the focus of the upper'surface, and if the light source be then located at any point between these two foci, every condition hereinbefore pointed out will be completely attained.

However the preceding explanation applies only to the up er and lower portions of thereflecting sur aces, and ignores their horizontal or intermediate portions corre-' sponding generally to the region included between the lines 12-6 and 00 of Fig. 10.

merely to merge one surface into the other at this point, it will be found that the'reflection of the light according to these two systems will produce an uncertain and confused reflection. Therefore according to my invention I connect these two parabolic surfaces by a surface which in cross section is everywhere inclined from below inwardly as shown in Figs. 3 and 4, the resultbeing that the light rays striking this part of the reflector are also thrown downwardly where they will aid the operation of the vehicle and avoid any blinding effect. 4

In Figs. 1 to 5 inclusive, I .have illustrated some actual reflectors containing these improvements. 1 represents face corresponding to the portion B in Fig. 10, and 2- a section of a second surface corresponding tothe portlon C in Fig. 10. Each of theseparabolic surfaces and if a second com be effected by makwill naturally not be secured, but al In Figs. 1, 2 and 3, a segment of a parabolic sur- 1 parabolic is terminated before it reaches the horizon tal, the upper reflector at the line 33, and the lower reflector along the line 4-4: angularly related therewith. The angular space defined between these lines is occupied by a reflector portion 5,.whichi1aturally in clines inwardly from the fact that the parabola 2 is larger than the parabola 1 so thatv the desired direction of reflection is secured. However it should be understood that these views are very greatly exaggerated for purposes of clearness, and that in practice the benefits of my invention will be secured with inclinations and divergences very much less than those here shown.

The light source will ordinarilyconsist of o ing to the factthat the source of light producedbyan incandescent lamp bulbis not a geometrical point, but is a region of appreciable size, notwithstanding the compactness of construction in lamps providedfor this use, the exact theoretical requirements of the precedin demonstration canpractical features thereof: are obtained when the lamp bulb is so arranged that the rearward or inward portion of its filament traverses substantially the point awhile the outermost portion is above and preferably inside the point 6, which condition can easily be obtained.

In Figs. 4 and 5 I have illustrated a modiupper parabolic surface 10 and thelower parabolic surface 11 are of the same size, the axis of the lower. being inclined from the horizontal as before. In ordef to provide the inclined lateral portions of the reflector which are characteristic of my invention, I flare slightly outwardly the u perv most portions of the lower parabol shown at 1212, and I draw slightly inwardly the lowermost portionsof the upper parabola as shown at 131 3, thus providing for the inclined portions 1414.

It will be understood that the illustration in Figs. 4 and 5 is much exaggerated for purposes of clearness. With this arrangement the focal points of the two surfaces are arranged as shown in Fig. 5, 0 representing the focus of the upper surface and (Z that of the lower surface. The lamp 15 is located so that its filament falls just forward of the focus a and above, though also slightly forward of the focus d. In this .case the rays striking the upper parabola will be thrown downwardly by the converg- 1 fication of my said 1nvent1on wherein the v 1 aas' ing action and thus striking the lower parabola will be thrown c downwardly by reason of the inclination of that parabola. and by reason of the location of the source above its axis.

In Fig. 11 I have illustrated the effect of employing my improvements upon an automobile, wherein indicates one of the front wheels and 21 one of the forward lamps. The converging effect of the upper half of the reflector throws the rays 22 downwardly but to a considerable distance in front of the machine; the diverging effect of the 4 lower half of the reflector sends the rays lamp having a reflector whose upper part is 23 also downwardly beneath the first rays, while also spreading them over the road surface; the side portions of the reflectors direct the rays even more sharply downward as shown at 24:, covering the road near and at the sides of the machine. It will be understood that the angles are shown as excessively sharp in this drawing because of.

limitation of space.

WhileI have described my invention in detail itwill be apparent thatnumerous variations may be made in such details and in the application of those details to various lamps, wherefore I do not restrict myself except as required by the claims hereto ans nexedor the prior state of the art.

Having thus described my invention, what I claim is V I 1. The combination with'a vehicle of a of parabolic shape with its axis substantially horizontal and whose lower part is of parabolic shape with its axis inclined downwardly, said lamp having a light source located substantially on the axis of such upper surface and above the axis of such lower surface and forward of the focal point of such upper surface. j 2. The combination with a vehicle of a lamp having a light source and a reflector whose upper part is adapted to converge the light from said source, whose lower part is adapted to disperse the light from said source, and whose lateral portions are adapted to throw downwardly the light from said source. I I

3. The combination with a vehicle of a lamp having a reflector whose upper'part is of parabolic shape with its axis substantially horizontal and whose lower part is of parabolic shape with its axis inclined downwardly and whose lateral parts are independent of both parabolic portions and in clined inwardly, said lamp having a light source above the axis of the lower parabola and forward of the focal point ofthe upper parabola and near the axis of said upper parabola.

4:. A lamp reflector having its upper and lower parts formed as separate surfaces of revolution arranged substantially about a common axis, and having its intermediate shape with its focal point inside said source and its opposite side of parabolic shape with its focal'point outside said source and with its intermediate portion separate from both said parabolic surfaces and arranged to throw the light toward the side of said second surface.

7. A lamp reflector having a pair of opposed semi-parabolic reflecting surfaces whose adjacent edges are connected by inclined portions whose cross sections upon planes transverse to the parabolic axis are substantially straight.

8. A reflector having a pair of opposed semi-parabolic reflecting surfaces arranged in flaring relation to each other, the adjacent marginal portions of said parabolic surfaces being connected by a reflecting surface distinct from each of them.

9. In a lamp, a reflector having a pair of opposed semi-parabolic reflecting surfaces arranged in flaring relation to each other, the adjacent marginal portions of said surfaces being connected by non-paraboloidal reflectin surfaces, and a lightsource located substantially at the axis of one surface and at one side of the axis of the other surface.

10. In a lamp, a reflector having a pair of opposed semi-parabolic reflecting surfaces arranged in flaring relation to each other, a

' light source located substantially at the axis of one surface, and at one side of the axis of the other surface, and intermediate reflecting surfaces one at each side of the lamp and connecting the adjacent margins of the parabolic surfaces, said intermediate surfaces being arranged to reflect the light falling thereon in a direction past the axis which is the farther from said light source.

11. A reflector having a pair of opposed semi-parabolic surfaces, one being of larger diameter than the other and the two surfaces being continuous at their vertices whereby arate'd, and a light source located between said focal points. 13-. A reflector having a pair of opposed 130 semi-parabolic surfaces,

one being of larger diameter than the other, the two surfaces having a substantially common vertex and having their axes diverging from that point.

14. In a lamp, a reflector having a pair of opposed semi-parabolic surfaces,

surfaces having asubstantially common vertex and having their axes diverging from that point, and a light source located substantially upon the axis of the smaller parabolic surface between the focal points of the two parabolic surfaces.

15. A reflector having a pair of opposed semi-parabolic surfaces, one being of larger diameter than the other and the two surfaces being substantially continuous at their vertices, the adjacent marginal edges of the parabolic sections being joined by a reflect- 1ng surface which is separate from each of them and is inclined at every point toward the smaller parabolic surface.

16. In a lamp, a reflector having a pair of opposed semi-parabolic surfaces located upon opposite sides of a single light source, said surfaces substantially meeting each other at points near the foci and diver 'ng gradually with increasing distances rom said foci, and a reflecting surface bridging the gap and arranged to reflect the rays from said source toward one of said parab- 'olas.

17. In a headlight, the combination of a pair of opposed semi-paraboloid reflecting surfaces having their axes angularly disposed, the axis of the upper portion being substantially horizontal and that of. the lower ortion inclined downwardly and forwardly, and a light source located on the axis of the upper and above the axis of the lower.

18. The combination with a semi-paraboloid reflecting surface, of a second generally semi-paraboloid reflecting surface op osed thereto, the foci of the two surfaces eing spaced at different longitudinal points and their axes being divergent. I 19. The combination of a reflecting member, comprising a pair of approximately semi-parabolic surfaces op osed to each other, and one or more surfaces additional thereto and interposed between-them.

20. In a lamp a reflector comprising upper and lower parabolic sections, a source of light located substantially upon the axis of the upper section, there being on each side of the source of light and between the sections a reflecting surface arranged to re fleet rays from said source downwardly and forwardly through 'the open front of said reflector.

21. In a reflector a pair of opposed paraboloid sections of which one at least subtends less than 1809, whereby a -'gap is formed between their adjacent margins, and

one being of larger diameter than the other, the two independent reflecting surfaces interposed 1n said gap and arranged to reflect the rays falling thereon forwardly through the open front of said reflector and to one side of its axis;

22. In a headlight, a reflector having a. pair of opposed paraboloid sections arranged w1th their axes diverging, neither subtending an angle greater 'than 180, whereby a gap is formed between their adjacent margins, and independent reflectin surfaces located in said gap and arrange to reflect the rays falling thereon downwardly and forwardly through the open front of said reflector.

23. A headlight for automobiles comprising, in combination, a reflector having a pair of opposed semi-paraboloid surfaces arranged one above the other, the axis of one at least being substantially horizontal and subtending less than 180, and a light source on the axis of said surface.

24. In a headlight, a reflector having a spect to a vertical plane and subtending less than 180 whereby no part of the light reflected by that portion will be thrown laterally in a horizontal plane. i

26. A reflector having diflerent parts of different sized paraboloids, all having a common vertex.

27. In a headlight, a one-piece reflector containing independent paraboloid surfaces having a common vertex and spaced focal points, and a light source located between said focal points' 28. In a lamp, a reflector made in one piece having opposed paraboloid surfaces whose margins are spaced apart, and a simple curved surface connecting said margins and having its normals falling upon one side of the lamp axis.

29. In a lamp, a reflector having a pair of opposed parabolic reflecting portions arranged with .their axes in angular relations and united by flat faces at each side thereof.

30. In a headlight, a reflector made in one piece and having a pair of opposed semiadditional reflecting faces between the paraboloid surfaces.

31. In a lamp, a light source, and a reflector having one of its sides of parabolic shape with its focal point inside said source and its opposite side of parabolic shape with its focal point outside said source, the opposite sides of said reflector being continuous through a common vertex.

32. In a lamp, a reflector having its opposite sides of parabolic shape but of unequal parameter, and having a common vertex whereby the focal point of one portion lies nearer said common vertex than the focal point of the opposite portion, and a light source located at a distance from said common vertex intermediate the distances of said two focal points.

33. In an automobile headlight, the combination of a pair of opposed semi-paraboloid reflecting surfaces located one above the other and having their axes flaringly disposed, and a light source located on the axis of the upper surface and above the axis of the other surface.

34. A lamp reflector having its upper and lower parts formed as the surfaces of revolution of different generators, said surfaces being arranged substantially about a common axis.

35. A reflector for automobile lamps having its upper and lower portions of unequal size of semi-paraboloid form, the upper portion having its axis horizontal and the lower portion having its axis inclined downwardly at a smallangle.

In testimony whereof, I hereunto affix my signature.

WILLIAM H. WOOD.

DISCJLAIIJIEB.

1,235,275.- William H. Wood, Cleveland, Ohio.

1917. Disclaimer filed April 30, 1921, by the patentce.

LAMP. Patent dated July 31,

Enters this d'mclaimer- "To that part of the claim in said specification, being claim 34 thereof, which is in the following words, to wit:

34. A lamp reflector having its upper and lower parts formed as the surfaces of revolution of different generators, said surfaces being arranged substantially about a common axis."

01554; Gum, m 10, 1921.1 

